This application claims the benefit of Korean No. 2001-12241, filed Mar. 9, 2001, in the Korean Industrial Property office, the disclosure of which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to a system to which power is supplied using a switching mode power supply (SMPS), and more particularly, to a power supply control apparatus, which is capable of reducing power consumption by a SMPS in the system, such as a facsimile machine, for transmitting, receiving, and outputting data, and a method thereof.
2. Description of the Related Art
A switching mode power supply (SMPS) provides electric power to electric loads with a switching operation. A conventional SMPS, which is included in a system, such as a facsimile machine, for outputting data, is shown in FIG. 1. FIG. 1 illustrates an example in which power is supplied to a system controller (CPU) included in a system and peripherals from the SMPS included in the system.
Referring to FIG. 1, in the conventional SMPS, an alternating current (AC) voltage is changed into a direct current (DC) voltage by a rectifier circuit 101, and the DC voltage is transmitted to a driving voltage-applying portion 105 and a primary winding Np when an AC switch SW1 is turned on. In this case, a driving voltage Vcc is not applied to a pulse width modulation-integrated circuit PWM-IC 110, and thus power is induced in a primary winding Np. The driving voltage-applying portion 105 includes start up resistors R1 and R2, a capacitor C1, a resistor R3, and a diode D1 and supplies the driving voltage Vcc to the PWM-IC 110. That is, when the DC voltage is applied to the driving voltage-applying portion 105, the capacitor C1 is charged through the start up resistors R1 and R2. Due to the voltage in the capacitor C1, the driving voltage Vcc is supplied to a terminal P1 of the PWM-IC 110. As a result, the PWM-IC 110 outputs a signal for controlling a switching operation of a field-effect transistor (FET) through a terminal P3. An output switching control signal is applied to a gate terminal of the FET through a resistor R4. A resistor R5 is connected between the FET and a ground. When the FET is turned on, the primary winding Np in a transformer 115 allows the power to be induced in secondary windings Ns1 and Ns2 and in an auxiliary winding Na.
When the power is induced in the auxiliary winding Na of a transformer 115, the driving voltage Vcc is supplied to the PWM-IC 110 through the diode D1 and the resistor R3 in the driving voltage-applying portion 105. In a case where the FET is turned off and thus power is not induced in the auxiliary winding Na, the driving voltage Vcc is supplied to the PWM-IC 110 by the voltage charged in the capacitor C1.
As above, the power, which is induced in the auxiliary winding Na and the secondary windings Ns1 and Ns2, is determined in accordance with the switching operation of the FET. The switching operation of the FET is performed in accordance with a duty cycle, which is determined in the PWM-IC 110 according to a feedback signal provided from a feedback portion 120 through a terminal P4. The feedback portion 120 senses a voltage Vo1 output to the system controller (not shown) and provides a feedback signal to the terminal P4 of the PWM-IC 110 so that the output voltage Vo1 is maintained at a constant level. The PWM-IC 110 measures the peak value of current flowing into the FET through a terminal P2 and thereby prevents over-current from flowing into the FET. That is, in a case where it is recognized that the over-current flows into the FET in accordance with the measured peak value of the current, the PWM-IC 110 shuts down the FET.
Meanwhile, AC power induced in the secondary windings Ns1 and Ns2 is smoothed into a DC voltage by diodes D2 and D3 and capacitors C2, C3, C4, and C5, respectively, and thus is supplied to peripherals (not shown) and to the system controller.
However, when an AC switch SW1 is turned off, the SMPS shown in FIG. 1 stops working to supply the power to the peripherals and the system controller, as described above.
Likewise, the conventional SMPS continuously supplies power to the system controller and the peripherals in a case where the AC switch SW1 is not turned off. Thus, in order to reduce power consumption, the AC switch SW1 must be turned off when the system is not used. However, it is unknown when the output of data is required in the system, such as a fax machine, and thus the system always turns on the AC switch SW1. Thus, the power is continuously applied to the system controller and to the peripherals even when the system is not used, thereby unnecessarily consuming power.
To solve the problem, in the related art, a sleep mode has been suggested for cutting off power supplied from the SMPS to all of the peripherals of the system except the system controller in a case where it is recognized by the system controller that the system has not performed an operation for a predetermined period of time, has been suggested. However, even in a case where the sleep mode is set, the SMPS continuously supplies power to the controller, and the work for supplying power from the SMPS to the peripherals is continuously performed even though the power supply of the SMPS to the peripherals is cut off. Thus, even in a case where the sleep mode is set, power continues to be consumed in the SMPS.
To solve the above problems, it is a first object of the present invention to provide a power supply control apparatus, which controls the operation of a switching mode power supply (SMPS) so that power consumption in a system including the SMPS is reduced, and a method thereof.
It is a second object of the present invention to provide a power supply control apparatus, which controls to operate a SMPS only when power to a system is required, without a need for an alternating current (AC) switch, and a method thereof.
It is a third object of the present invention to provide a power supply control apparatus so that a system, such as a fax machine, is automatically turned on only when the output of data is required, and a method thereof.
Additional objects and advantageous of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Accordingly, to achieve the above and other objects, according to the present invention, there is provided an apparatus for controlling power supply to each part in a system including a system controller and a data output device. The apparatus includes a switch that is set to an ON state by a user""s contact, a detection portion which is connected in parallel with the switch and for detecting whether a signal for requiring a predetermined operation is applied to the system from outside, and a power supply portion for supplying power to each part of the system when the switch is temporarily set to the ON state or a second signal for indicating the detection of the signal is input from the detection portion, and for terminating the power supply to each part in the system including the system controller when a power off signal is applied from the system controller when the switch is set to an OFF state or when the second signal for indicating the detection of the signal is not input from the detection portion.
In order to achieve the above and other objects, according to the present invention, there is provided an apparatus for controlling power supply to a system having a system controller and peripherals requiring the power supply. The apparatus includes a switch that is controlled to turn on/off by a user, a first switching unit, a pulse width modulation (PWM) portion that supplies a pulse signal for controlling the switching operation of the first switching unit when a driving voltage is applied, a transformer that supplies power in accordance with the operation of the first switching unit, a driving voltage-applying portion which applies the driving voltage to the PWM portion when the switch is turned on, and a power-off signal detection portion which stops the operation of the PWM portion when a power off signal is detected. The system controller generates the power off signal when a predetermined period of time passes after power output from the transformer is applied, and then, a sleep mode is set.
The apparatus further includes a detection portion for detecting whether a signal for requiring a predetermined operation is applied to the system from outside, and the driving voltage-applying portion is connected to the detection portion so that the driving voltage is applied to the PWM portion when a second signal for indicating the detection of the signal from the detection portion is applied.
In order to achieve the above and other objects, according to the present invention, there is provided a method of controlling power supply in a system which supplies power output from a power supply function portion to a system controller and peripherals. The method includes controlling the power that is supplied to the peripherals and the system controller from the power supply function portion either when a switch that is set to an ON state if a user is in contact with the switch, or when a signal for requiring a predetermined operation is applied from outside the system, and controlling the power supply function portion to terminate the power supply to the peripherals and the system controller when a power off signal is generated from the system controller in the state where power is supplied to the peripherals and the system controller.